There have been a number of attempts to build gravitomagnetic induction devices, and a small number of reports of gravitomagnetic induction like effects had found a place in scientific literature. But none of the examples that follow are accepted as reproducible examples of gravitomagnetic induction; nor is there any prior art on a device to produce gravitomagnetic induction utilizing a head disk assembly.
Gyroscopes produce a force when twisted that operates “out of plane” and can appear to lift themselves against gravity. Although this force is well understood to be illusory, even under Newtonian models, it has nevertheless generated numerous claims of gravitomagnetic induction devices and any number of patented devices. Perhaps the best known example is a series of patents issued to Henry William Wallace, an engineer at GE Aerospace in Valley Forge, Pa., and GE Re-Entry Systems in Philadelphia. He constructed devices that rapidly spun disks of brass, a material made up largely of elements with a total half-integer nuclear spin. [A “kinemassic field” generator from U.S. Pat. No. 3,626,605: Method and apparatus for generating a secondary gravitational force field.] He claimed that by rapidly rotating a disk of such material, the nuclear spin became aligned, and as a result created a “gravitomagnetic” field in a fashion similar to the magnetic field created by the Barnett effect.
Hayasaka and Takeuchi had reported weight decreases along the axis of a right spinning gyroscope. Tests of their claims by Nitschke and Wilmath yielded null results. A few years later, recommendations were made to conduct further tests. Provatidis and Tsiriggakis have proposed a novel gyroscope equipped by couples of rotating mass particles that draw only the upper (or lower) 180 degrees of a circle, thus producing net impulse per full revolution. This is achieved by transforming the previously used circular orbit into a figure-eight-shaped path (symbol of infinity) of variable curvature that entirely lies on the surface of a hemisphere. Moreover, it was claimed that the spinning of the entire mechanism, in conjunction with the resonance of the centrifugal force through two servomotors, produces antigravity propulsion towards the axis of symmetry of the aforementioned hemisphere. [Antigravity Mechanism, U.S. Patent Application No. 61/110,307 (Filing date: 31 Oct. 2008) In November 2011, Professor Provatidis published a detailed state-of-the-art report.
The Russian researcher Eugene Podkletnov claims to have discovered experimenting with superconductors in 1995, that a fast rotating superconductor reduces the gravitational effect. Many studies have attempted to reproduce Podkletnov's experiment, always to no results.
A paper by Martin Tajmar et al. in 2006 claims detection of an artificial gravitational field around a rotating superconductor, proportional to the angular acceleration of the superconductor.
In July 2007, Graham et al. of the Canterbury Ring Laser Group, New Zealand, reported results from an attempt to test the same effect with a larger rotating superconductor. They report no indication of any effect within the measurement accuracy of the experiment. Given the conditions of the experiment, the Canterbury group concludes that if any such ‘Tajmar’ effect exists, it is at least 22 times smaller than predicted by Tajmar in 2006. However, the last sentence of their paper states: “Our experimental results do not have the sensitivity to either confirm or refute these recent results [from 2007]”.
Referring to FIG. 2A the glide head 200 flies with a pitch angle with the trailing end 208 closer to the surface of the disk than leading edge 206. Due to the pitch angle during flight and because glide head 200 includes trailing end taper 218, the lowest flying point 234 on glide head 200 is moved forward of the trailing end 208, and is at the junction of the air bearing surface 214, 216 with trailing end taper 218.; FIG. 2B, show a bottom plan view and a side view, respectively, of a glide head 200 having side rails with tapered trailing ends. As shown glide head 200 includes first and second rails 202 and 204 that run from the leading end 206 to the trailing end 208 of glide head 200 with a recessed area 222 formed between the two rails 202 and 204. Rails 202 and 204 include a leading end taper 210 and a trailing end taper 218 with air bearing surfaces 214 and 216 disposed between. Also as shown glide head 200, in, including rail 204 and the angle of leading end taper 210 and trailing end taper 218. Recessed area 222 is indicated by a broken line. Glide head 200 is a 50% slider. The term “50%”, as is well known in the art, refers to the size of the slider. It should be understood; however, that glide head 200 is not limited to a 50% slider, but may be any size desired.
FIG. 3A illustrates a magnetic head with combined elements of the read and write functions into a single, or a “merged head” using the IBM terminology as well as a writing head. The small, concentrated magnetic field magnetizes, or “turns on”, a region on the disk by induction. The gap at the bottom concentrates the field over the disk. When current is applied to generate the magnetic field, the “hard” disk medium is permanently magnetized with a polarity that matches the writing field. Reversing the current reverses the polarity on the disk bit to rewrite or erase the information stored in digital format. A timing clock is synchronized with disk rotation so that the location of the head with the magnetic “bit cells” is precisely known and controlled. Bits represent ones and zeros (reversed magnetic polarity). Although the disk is permanently magnetized, bits are easily reversed, or rewritten, as the head applies an opposite magnetic field produced by simply reversing the coil current. MR and GMR require more precise synchronization since the magnetic domains are smaller. The task of the READ portion of the head is to read the disk data bits. Reading is where the state-of-the-art technology is being applied and where MR and the newest GMR principles are being applied. Both MR and GMR use a somewhat similar head structure. The very thin MR or GMR sensor strips are sandwiched between oppositely biased contact elements and this component is placed between two magnetic shields to reduce stray magnetic fields. MR and GMR head structures are shown. The Soft Adjacent Layer (SAL) is magnetized by the nearby field. The SAL produces a magnetic field that biases the magnetization in the MR element so that its magnetic field angle is shifted to 45°, the optimum angle for this type of sensor. Although reading and writing are independent functions, it is critical to place the write and read heads close together and near the recording medium. Writing heads are therefore fabricated directly onto the spin valve GMR reading heads. The top shield of the GMR sensor becomes the bottom magnetic pole of the writing head as shown in FIG. 3a to form an integrated or merged head design. The GMR head and writing head share one magnetic layer. The efficient integrated Read-Write assembly is referred to as a merged head. The write head may be less than 30 microns above the rapidly spinning disk and the transaction is virtually instantaneous. In future, higher density may require a near-zero gap.
FIG. 3B illustrates one embodiment for a printed circuit board for use in the head-disk assembly. A printed circuit board 400 includes multiple layers including a power plane, ground planes, and signal paths. In general the printed circuit board includes, for operation of the hard disk drive, digital circuits 356, clock 340, analog circuits 360, and control/power and line conditioning 370. A head-disk assembly [HDA] connector 330 connects power and control conductors from the printed circuit for routing to the head-disk assembly. For this embodiment, the ground plane is divided between a digital circuit ground plane 310 and an analog circuit ground plane 320. A clock 340, used to generate data to read and write data in the hard disk drive, is mounted on the printed circuit board 300 and coupled to the digital circuit ground plane 310. Similarly, digital circuits 350 that control the operations of the hard disk drive are also mounted on the printed circuit board and grounded on the digital circuit ground plane 310. Analog circuit 360, which operates on analog signals read from the head-disk assembly, is mounted on the printed circuit ground plane 320. The power and control signals from the analog circuits 360 are input to control/power line conditioning circuits 370 conditioning the power and control signals to reduce noise coupling in the actuator. The conditioned signals are then passed to the HDA connector 330.
FIG. 4 illustrates a glide head or a downward facing merged head mounted on a suspension arm 420 and flying over the surface 424 of a rotating disk 422; disk 422 rotates in the direction of arrow 425. A linear actuator (not shown) controls the radial position of the head 402 with respect to the disk 422 by moving the suspension arm 420 as illustrated by arrow 421.
FIG. 5 illustrates a side view of a downward facing glide head, or a downward facing merged head. It should be understood that typically, the top surface 424A and the bottom surface 424B of disk 422 is utilized at the same time by a downward facing head 402A and an upward facing head 402B, respectively, as shown in the side view illustrated in FIG. 5. Head 402A and 402B are mounted on respective suspension arms 420A and 420B, which are controlled by linear actuator 428. During operation, disk 422 rotates to produce a linear velocity between disk 422 and head 402. The higher linear velocity drives air between the surface 424 of the disk 422 and the head 402, which produces lift on an air bearing surfaces 214 and 216 (ref FIG. 2) of head 402. This, head 402 is said to “fly” over surface 424 of disk 422. As disk 422 rotates, head 402 is moved laterally over a radius of disk 422 by linear actuator 428 (shown in FIG. 5). The lateral movement of the head 402 is slow relative to the rotation of the disk 422. During operation of the mechanical force mass spin-valve device the glide head 402 experiences a mechanical force from Nano-pits or Nano-bumps on the disk 422 surface. Likewise; during operation of the magnetic force mass spin-valve device the merged head 402 experiences a magnetic force produced from Nano-pits or Nano-bumps on the disk 422 surface.